This invention relates generally to the production of mixed yarns from two or more distinct varieties of continuous synthetic filaments from molten organic compositions and, more particularly, to a spinneret assembly useful in the spinning process.
Yarns containing two or more distinct varieties of continuous synthetic filaments are used increasingly in the textile industry. The filament varieties may differ in any or all of composition, shrinkage, dyeability, color, electrical conductivity and the like. Intermediate yarns separately spun from the individual compositions are often plied, with or without a filament-intermingling treatment, to create any desired mixed-filament yarn. More recently, mixed filament yarns have been prepared directly during spinning by passing two (or more) polymer melts individually through the same spinning pack to issue simultaneously through spinning capillaries in a single spinneret plate as taught by Reese in U.S. Pat. Nos. 3,593,513 and 3,681,910. The extruded filaments may be wound up with or without additional mechanical drawing and with or without a filament-intermingling treatment.
The design of a spinning pack for extruding two (or more) polymer melts depends on the number of mixed-filament yarns to be produced. The extrusion of a single multifilament mixed-filament yarn is relatively free of complications. Frequently, it is desirable, however, to extrude more than one yarn from the same spinning pack, that is, to provide more than one grouping of spinning orifices in the spinneret plate. It is apparent that proper distribution of two melts to selected spinning orifices in multiple groupings creates design difficulties. Heretofore, in order to maintain symmetry of flow lines involved, it has been the practice to use an even number of groupings, i.e., usually two. The fiber producer ordinarily must modify existing equipment for producing mixed-filament yarns. When a given melt-flow capacity is available, it may result that greatest productivity is obtained only with an odd number (usually three) of groupings of spinning orifices. However, the use of an odd number of orifice groupings has been less than satisfactory because of unacceptable filament-to-filament denier nonuniformities created within each extruded yarn as well as excessive yarn to yarn denier differences.